Dak

So I rebuilt my engine a couple years ago. Did a street port on the 6-port block since I had a spare set of irons. I had to buy rotor housings as mine were shot. So I street ported some Turbo ones. Now jump to the present. I'm still happy with it though I still haven't went standalone I guess I'm not fully getting everything out of the port I have but something still nags a little. Could I have went with a TII block or 13b-re, street ported it and ran it with the my stock ecu? If so would it have made better power than my 6-port even on the factory ecu? From what I gather the 4 port is a better base to start with even on a n/a. The timeframe I built mine was when RedRX I believe made 230whp ton a 13b-re block. At the time I thought man I'd like to go with the 4 port but I don't have the money for a rebuild and a standalone so I figured I was stuck with the 6-port and went that way. Was I wrong?

peejay

I don't see why it wouldn't have worked. Fuel and timing wouldn't have been ideal but they aren't ideal with a stock ECU for any application, anyway.

farberio

iTrader: (7)

4port NA = standalone

BLUE TII

iTrader: (9)

The factory NA ECU can handle a stock or street port 4 port rotary fine, it has AFM to make adjustments to engine VE.

You will make more power on a stand alone.
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OP, I wouldn't despair having rebuilt the 6 port engine.

If you are now ready for more power you can add a Holley 4150 style intake manifold, two 1,000-2,000cc injectors in the stock primary location/rail, 4150 EFI throttle body and a stand alone to the 6 port and make up to 200rwhp.

Once you are ready to build a 4 port NA motor you just buy the 4 port 4150 intake manifold for it and put your EFI/TB on that and re-tune. 200-250rwhp depending on port (stock to bridge).

Dak

This is actually what I would like to do once I get a standalone. It also seems this setup would be more flexible down the road if I decided I wanted to go turbo one day.

rotarygod

iTrader: (1)

The Holley manifold is all about top end power. It doesn't do well in the low to midrange. The runners are too short. It does flow very well though. Honestly, and this may sound weird, for a street use 4 port engine a TII intake manifold makes more usable power. It's surprisingly good. Better than any of the NA manifolds.

Dak

How would the TII intake work on the 6-port if port matched like Aaron Cake shows in his write-up on turbocharging the 6-port? I've always been leaning toward the PowerFC though I've been considering the Adaptronic cause I didn't know if the PFC would work with the Holley TB. Maybe I should use the TII manifold with a PowerFC and call it good for now since Banzai has base n/a maps available for the PFC. My goal has always been 200whp which though rare has been done on the 6 port.

All that said the 230whp made by RedRX was with the 13B-RE intake manifolds(Granted it was a 4 port). How much different is the RE intake from the TII?

Here is the porting link for any that haven't seen it.
Porting The 4 Port Turbo II Lower Intake To Fit The 6 Port NA Block

peejay

I will respectfully disagree. One of the best things I did to my TII engine was put a S4 N/A intake on it. Made more power down low and the RPM range extended significantly. It was the best of both worlds.

The TII intake has more cramped bends which hurts velocity. This was the compromise Mazda made in order to fit a turbo next to it and an intercooler on top.

I've never run a Holley manifold with EFI on anything but my bridge port but one thing it does not lack is low end or midrange.

peejay

Don't do it. This does horrible things for airflow at that critical junction - you're trying to diffuse the airflow and turn at the same time. That never ends well. The manifold is already bad for this and then opening it up to match with a 6 port will be even worse.

It's very good at clearing a turbocharger. That is all it is good for. If you have no turbocharger, aluminum is 50 cents a pound at the recycler's.

BLUE TII

iTrader: (9)

rotarygod

The Holley manifold is all about top end power. It doesn't do well in the low to midrange. The runners are too short. It does flow very well though.

I don't disagree with this.
The traditional focus on NA performance is high rpm power and really tight gearing. RPM increase without torque drop off = more HP.

Do you know how the Holley 6 port manifold compares to wired open 6 ports on a stock NA intake manifold (which is what the OP and many others are using)?
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Once you go 4 port you can regain low end/midrange NA power with porting for overlap.
Cheap/easy is bridge porting: expensive/harder is semi p-port or full p-port.

Both port styles without the late closing timing (typical of race engines) if you want low/midrange power.

Dak

Well going by this article on Borla's site: http://www.borlainduction.com/media/carb_vs_fi.pdf the RB holley manifold makes more peak power than the Dellorto carbs on a 6 port LIM, but the Dells powerband was broader. The Haltech & ITB's smoked 'em both. I'd like to see how a Holley TB and EFI would compare. ITBs may be the best choice but doesn't seem as flexible as far as turbocharging down the road goes. Also I would probably use the JW or Pro-jay intake rather than the RB since they will clear a turbo. First I need a standalone. I'll cross the intake bridge when I get there I guess.

P.S. HP numbers in that article looks to be at the crank as I think all their tests were on an engine dyno.

peejay

Was your first clue, the image of an engine on an engine dyno?

Need to be careful when comparing carbureted powerbands. The type of carburetor can make as much of a difference in powerband as the manifold geometry. A carb with poor atomization will make less power than a carb with good atomization and this even assumes that you can get it tuned to deliver the fuel the way you want it. A lot of times you simply can't unless you want to play mad scientist re-engineering the various metering circuits.

Dak

Maybe. Hey everyone might not be as perceptive as I.

rotarygod

iTrader: (1)

I know what those bends look like but they don't flow as poorly as your eyes think they do. As I said, they are surprisingly good. The S5 na manifold on the other hand is a piece of junk.

rotarygod

iTrader: (1)

A Holley manifold with a throttlebody and fuel injection will make great top end power but will be down in the low to midrange compared to stock manifolds. In my opinion it's not a worthwhile tradeoff for a street car.

peejay

I picked up a lot of time in the quarter mile and had to add fuel everywhere when I replaced the TII manifold with the N/A. Powerband extended tremendously, as well, with the old manifold it was dead over 8k but with the N/A manifold it carried on quite a bit longer.

This was admittedly with a bridge port which relies more heavily on runner inertia. I'd still really like to try the N/A manifold on a street ported T2 but, to be honest, that is a lot of work for a subject that I don't care about anymore. I like the Holley manifold even more

rotarygod

iTrader: (1)

With a stock ratio transmission, there's no point to revving over 8k. That should be the shift point at the highest. Max average power should be based solely on gearing with peak occurring somewhere around 7k with anything above 8k being completely irrelevant.

peejay

I approach things scientifically. I try different shiftpoints and watch for changes.

My current engine's horsepower peaks around 8000 or so but I kept going quicker and quicker until I was shifting 1-2 at 10k and 2-3 at 9700 or so. No, the transmission does not like this. I originally did it just so I could get datalogs that high but I found that the car slowed down when I shifter at more sane speeds. It is average power that counts, so you have to shift quite a bit after peak. Ideally the horsepower is the same before and after the shift, so you have to set your gear window evenly over the horsepower peak.

If I had a close ratio trans, I could shift at lower RPM. According to datalog, 1-2 upshift at 10341rpm makes the revs drop to 6008... and it took a whopping .5 seconds to shift That doesn't look right to me, as the next record (10hz sampling) is 6800rpm. But I have datalogged .2 second upshifts at lower speeds.

I don't really remember (it was five years ago!) but I think I was winding the N/A-intake T2 engine no higher than 9500. I was out of injector and I was really worried about what might happen if the engine decided to come apart. I was still somewhat new to Atkins apex seals and didn't trust their rotor housing friendliness at high RPM.

Jeff20B

iTrader: (13)

You're talking about 2mm Atkins? Mine have been holding up great at 8000 RPM shifts with boost (9psi) and S4 NA rotors. I do shift slower than you though. My trans is S5 NA and a light steel flywheel.

Dak

Well since we've strayed from my original question and I think it's pretty much been answered anyway I'll throw this intake in the mix. Sometimes I think I'd like to fab something up that uses an FD TB( mainly for the newer style TPS) like this. I'd have to find someone to weld aluminum though unless I made it from aluminized steel tubing. I hope to start learning to weld soon. From what I read somewhere on here the TB isn't the restriction so putting a better flowing/different runner length manifold between it and the engine should in theory work well.


There was also another one Kahren built that didn't wrap over the motor but I didn't find it in a quick search. I think he did something close to 200whp, maybe 190whp with a Haltech so maybe it has potential.

peejay

That's just a big ITBc manifold that starves the primaries of air. The beauty of the N/A manifold (and to an extent the T2 manifold) is the way it uses the reversion of one rotor to charge the other. j9fd3s calls it the "ping pong manifold" because of that effect.

Dak

Yeah ,I always thought of it as ITB's that used the stock TB. I didn't realize that it starved the primaries. Maybe that's why he didn't make anymore power than people have made on the S5 intake. I have also wondered how much power one loses by ditching the "supercharging effect" of the stock one. I've also wondered if there was a way to incorporate it into a better flowing one with shorter runners.

I also read conflicting things like 200whp is all the S5 intake supports. Then someone else says 200whp is about all the 6 port does even ported and with a different manifold which makes it seem pointless and a waste of money to even ditch the stock one. The n/a realm is sort of no man's land as everyone (on the street at least) seems to go turbo. Which I'm not ruling out hence some of why I lean towards the holley style intake as I can bolt a turbo on at a later date without grinding and port matching and such on the TII LIM, or making a spacer for the turbo with the n/a LIM. From all the threads I've seen I don't know if I've seen a dyno sheet of a 6 port that broke 200whp( Renesis doesn't count).

peejay

It's hard for anyone to break 200whp with any kind of N/A without a lot of R&D time.

Mazdatrix had an E/Production 6-port that, by my guesstimate, made 270-280 crank HP but it took a lot of work to find how to do it, and then the question was engine longevity. IDA manifold and carb and some pretty extreme porting. Production does not allow bridge porting and Mazdatrix actually provided the SCCA with a guide to keep people from making cheater ports (define a street port as something where the leading side seal end does not cross an open port, VS defined as a single port opening)

I am unaware that the Holley manifold allows use of an OE-fit type turbo manifold. If they do, that's awesome, because I have been thinking of adding a turbo if/when I go dual-fuel. Mainly for the added cooling of E85.

BLUE TII

iTrader: (9)

Then someone else says 200whp is about all the 6 port does even ported

Mazdatrix had an E/Production 6-port that, by my guesstimate, made 270-280 crank HP but it took a lot of work to find how to do it, and then the question was engine longevity.

I was about to hold that Mazdatrix E-Prod motor up as an example too, but can you say it was 6 port motor when the secondary and aux ports were siamesed together to make it an extremely late closing 4 port motor? I believe they had to work hard on intake intake manifold/header length to get the power to peak under 10,000rpm?

I am sure that thing had no low end power with the large port runner volume.
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I theorize part of the problem with the 6 port engines NA and their 200-210rwhp peak power is that the round runners on the secondary ports and aux ports are pretty small and though the volume is adequate when added together you have the frictional losses of both runner wall area coming into affect on the overal port flow as well as turbulence from the transition from the single intake manifold into the 2 runners

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The 3rd gen RX-7 UIM is another good intake manifold for 4 port NA power (fits on S5 TII lower intake with some work).

350rwhp TII has shown 30rwhp gains under the curve simply switching to 3rd gen UIM/TB on back to back dyno runs (though little peak power gains). It lost some power below 2,600rpm and had a baby bump in power 3,900rpm to 4,700rpm and then the big bump in power 4,500rpm to 6,500rpm and a baby bump starting 7,100rpm.

https://www.rx7club.com/2nd-generati...fc-uim-655708/

3rd gen UIM uses the "Ping pong" effect (Mazda calls this Tournament effect or Dynamic Effect Intake *DEI*) most effectively of all manifolds on the 2ndary runner however the primary runners are short with an inline plenum (for throttle response?).

3rd gen RX-7 motors with turbos removed and a tune make 200-230rwhp- that is honking good.

Dak

The Jay-tech/Pro-jay and the JW do if I understand correctly or at least clear a turbo and aftermarket manifold. I am thinking the RB will not. Here are pictures of the JW on an engine and in a 2nd gen from this thread:
https://www.rx7club.com/rotary-drag-...ifolds-870086/

Granted he is using a tubular style turbo manifold.